JP2000013032A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin a board and to improve strength by forming etching resist on the copper foil of a specified copper-clad thermosetting resin adhesion film, selectively etching/removing the part of unnecessary copper foil and forming a fine opening part becoming a via hole. SOLUTION: A copper-clad thermosetting resin adhesion film 21 in which an adhesion layer comprising high molecular weight epoxy polymer which is obtained by blending and polymerizing bifunctional epoxy resin and halogenized bifunctional phenol so that epoxy group/phenol hydroxy group=1/0.9-1/1.1 and whose weight average molecular weight is not less than 100,000 is formed on copper foil is overlapped with an inner layer circuit board 1, vacuum press molding is executed and a copper-clad stacked board 4 with inner layer circuit is obtained. Etching resist 8 is formed on the surface of the outer layer copper foil and an opening part 51 is formed in a part where a via hole is formed. Thus, the via hole superior in mass production, connection reliability and an electric characteristic is provide. The board can be thinned and strength can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art In general, a multilayer printed wiring board is a resin-impregnated prepreg having a glass cloth as a base material between an inner circuit board having a circuit formed on a copper-clad laminate and a single-sided copper-clad laminate or copper foil. Then, it is heated and hardened by heating and pressurizing to form a circuit on the outer layer surface of the copper-clad laminate with the inner layer circuit bonded and integrated. With the recent miniaturization, high performance, and multi-functionality of electronic devices, multilayer printed wiring boards have become higher density, thinner between layers, finer wiring, and smaller diameter of interlayer connection holes. Interstitial via holes that connect only adjacent wiring layers (hereinafter referred to as
It is called a via hole. ) Has been used. Recently, it has been required to reduce the diameter of the via hole in order to further increase the wiring density.

As shown in FIG. 2A, a conventional method for manufacturing a multilayer printed wiring board having via holes involves a method of forming a circuit between an inner circuit board 1 having a circuit formed on a copper-clad laminate and a copper foil 3. As shown in FIG. 2 (b), a plurality of prepregs 9 are laminated and bonded by heating and pressing, and the copper-clad laminate 4 with the integrated inner layer circuit is shown in FIG. 2 (c). As described above, a hole is drilled at a predetermined position so as to reach the inner layer circuit, and a hole 5 for a via hole is formed.
As shown in (d), drilling of the through hole 6 is performed.
As shown in FIG. 2 (e), electroless copper plating or electroless copper plating and electrolytic copper plating 7 are formed, and the inner layer circuit and the copper foil are electrically connected, as shown in FIG. 2 (f). An etching resist 8 is formed on the outer layer copper foil, unnecessary copper is selectively removed by etching (shown in FIG. 2 (g)), and the etching resist is removed (shown in FIG. 2 (h)). It is. At this time, a single-sided copper-clad laminate may be used instead of the copper foil 3, and the through-hole 6 as shown in FIG. 2D may not be provided.

[0004] Conventionally, a method of using a polyimide film as a material capable of chemical etching and etching with hydrazine or the like is disclosed in Japanese Patent Application Laid-Open No. 50-4577.
JP-A-51-27464, JP-A-53-4906
No. 8 is known. Further, a method of etching (surface roughening, desmear treatment) a cured product of an epoxy resin used for a printed wiring board with concentrated sulfuric acid, chromic acid, permanganic acid or the like is disclosed in JP-A-54-144968 and JP-A-54-144968. It is known from JP 62-104197.

Further, recently, an insulating layer between conductor layers has
Conventional methods that do not use a substrate such as a glass cloth have been proposed and developed.

[0006]

In the conventional method for processing a hole for a via hole, a hole is drilled to a position reaching an inner layer circuit. Therefore, unlike the drilling of a through hole, the processing is performed by overlapping a plurality of holes. However, there was a problem that processing was performed one by one, which required a very long time and low productivity.

If the depth of the tip of the drill does not reach the inner layer circuit, the connection between the inner layer circuit and the outer layer copper foil cannot be performed. Therefore, it is necessary to stop the movement of the tip of the drill just at the position where the inner layer circuit is reached.To achieve this, the variation in the thickness from the surface to the inner layer circuit must be reduced. The variation in the thickness of the wiring board is considerably large, which causes poor conduction. Furthermore, when drilling a small diameter of 0.3 mm or less, there is a problem that the life of the drill is remarkably reduced due to processing of the resin layer containing the core of the drill and the glass cloth base material.

In the conventional method of performing chemical etching, hydrazine is highly toxic, and concentrated sulfuric acid, chromic acid,
Permanganic acid has been designated as a specific chemical substance, and safety needs to be considered.

Furthermore, a multilayer printed wiring board in which a base material is not used for an insulating resin layer sometimes has low strength. The lack of this strength means that if we focus only on the function as a multilayer printed wiring board, we can use it in places where strength is not required or attach a separate reinforcing plate. Multilayer printed wiring boards
In many cases, a semiconductor device having a narrow terminal interval is mounted, or a semiconductor itself is mounted on a multilayer printed wiring board, and a base for reliably performing soldering and wire bonding used in direct mounting is required.

The present invention provides a method for manufacturing a multilayer printed wiring board having via holes excellent in mass productivity, sustained reliability, and electrical characteristics, capable of being thinned, excellent in strength, and excellent in surface mounting. The purpose is to do.

[0011]

SUMMARY OF THE INVENTION A method of manufacturing a multilayer printed wiring board according to the present invention comprises the steps of: a. A bifunctional epoxy resin and a halogenated bifunctional phenol are combined with each other by an epoxy group / phenol hydroxyl group = 1 / 0.9 to
A high-molecular-weight epoxy polymer having a weight-average molecular weight of 100,000 or more and having a film-forming ability, which was blended so as to be 1 / 1.1, and was heated and polymerized in the presence of a catalyst; a crosslinking agent; An adhesive layer of a thermosetting epoxy resin composition containing an epoxy resin, a curing agent, a curing accelerator if necessary, and an inorganic filler was formed on a copper foil,
A copper-clad thermosetting resin adhesive film is prepared, an inner circuit board on which an inner layer circuit is formed in advance, and a resin surface of the copper-clad thermosetting resin adhesive film are superimposed and bonded by heating and pressing to form a laminate. Process. b. On the copper foil of the copper-clad thermosetting resin adhesive film, an etching resist is formed, and by selectively etching away unnecessary copper foil portions, a fine opening serving as a via hole is formed. Removing. c. The thermosetting epoxy resin composition exposed at the fine opening to be the via hole, an amide-based solvent, an alkali metal compound, an etching solution comprising an alcohol-based solvent,
A step of forming a hole to be a via hole by etching until the inner circuit is exposed. d. A step of plating at least the inner wall of the via hole by metallization to electrically connect the inner layer circuit and the copper foil. e. A step of forming an etching resist on the copper foil of the plated laminate and selectively removing unnecessary copper by etching to form an outer layer circuit and remove the etching resist. It is characterized by consisting of.

[0012] The inorganic filler can be blended in an amount of 10 to 60% by volume of the thermosetting epoxy resin composition.

As the inorganic filler, aluminum hydroxide, magnesium hydroxide, talc, alumina, magnesia, E glass, titanium dioxide, potassium titanate, aluminum silicate, calcium carbonate, clay, silicon nitride, and the like having electrical insulation properties are used. A material selected from the group consisting of silicon carbide, aluminum borate, powdered synthetic mica, or a combination thereof can be used.

As the inorganic filler, it is possible to use one selected from the group consisting of aluminum hydroxide, talc, clay, synthetic mica powder or a combination thereof having electrical insulation.

[0015] The amide-based solvent in the etchant of the cured thermosetting epoxy resin composition may include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone or a combination thereof. And an etchant present in the solution at a concentration of 30 to 95% by weight.

The alkali metal compound in the etching solution of the cured thermosetting epoxy resin composition is selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, and has a concentration of 0.5 to 15% by weight. And an etching solution present in the solution can be used.

[0017] The alcoholic solvent in the etchant of the cured thermosetting epoxy resin composition may be ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl. Using a material selected from the group consisting of ether, diethylene glycol monobutyl ether, triethylene glycol, tetraethylene glycol, polyethylene glycol or a combination thereof;
An etchant present in the solution at a concentration of 35% by weight can be used.

Instead of plating in step d, a conductive paste can be applied, dried and cured to electrically connect the inner layer circuit and the copper foil.

The present inventors have conducted various studies to obtain a resin composition that does not include a glass cloth substrate as a material that can be thinned and can collectively process via hole holes by chemical etching. As a result, chemical etching is possible. The present invention was able to be accomplished by finding a thermosetting epoxy resin composition and an etching solution thereof.

[0020]

DETAILED DESCRIPTION OF THE INVENTION (Thermosetting epoxy resin composition)
The thermosetting epoxy resin composition used in the present invention comprises an epoxy polymer having a film forming ability, a crosslinking agent, a polyfunctional epoxy resin, a curing agent, and an inorganic filler.

(High molecular weight epoxy polymer having film forming ability) The high molecular weight epoxy polymer having film forming ability is a so-called high molecular weight epoxy polymer having a weight average molecular weight of 100,000 or more, and is a bifunctional epoxy resin. And a halogenated difunctional phenol, the blending equivalent ratio of the bifunctional epoxy resin and the halogenated bifunctional phenol is set to epoxy group / phenolic hydroxyl group = 1 / 0.9 to 1.1, and the boiling point is increased in the presence of a catalyst. In an amide-based or ketone-based solvent at 130 ° C or higher, at a reaction solids concentration of 50% by weight or less,
It is obtained by heating and polymerizing.

(Bifunctional Epoxy Resin) The bifunctional epoxy resin may be any compound as long as it has two epoxy groups in the molecule.
Type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, aliphatic chain epoxy resin and the like. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the bifunctional epoxy resin may be contained as impurities.

(Halogenated Bifunctional Phenols) The halogenated bifunctional phenols may be any compounds having a halogen atom substituted and having two phenolic hydroxyl groups. Examples include functional phenols such as hydroquinone, resorcinol, catechol, and polycyclic bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols, and halides such as alkyl group-substituted products thereof. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the halogenated bifunctional phenols may be contained as impurities.

(Catalyst) The catalyst may be any compound as long as it has a catalytic ability to promote an etherification reaction between an epoxy group and a phenolic hydroxyl group.
Examples include alkali metal compounds, alkaline earth metal compounds, imidazoles, organic phosphorus compounds, secondary amines, tertiary amines, quaternary ammonium salts, and the like. Among them, alkali metal compounds are the most preferred catalysts. Examples of alkali metal compounds include sodium, lithium and potassium hydroxides, halides, organic acid salts, alcoholates,
There are phenolates, hydrides, borohydrides, amides and the like. These catalysts can be used in combination. The amount of the catalyst is generally 0.001 mol per 1 mol of the epoxy resin.
It is about 01 to 0.2 mol. When the amount is less than 0.0001 mol, the reaction for increasing the molecular weight is remarkably slow. When the amount exceeds 0.2 mol, the molecular weight is not increased linearly.

(Reaction solvent) The reaction solvent is preferably an amide-based or ketone-based solvent. The amide-based solvent is not particularly limited as long as it has a boiling point of 130 ° C. or more and dissolves an epoxy resin as a raw material and phenols. However, for example, formamide, N-methylformamide, N, N-
Dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N,
N ', N'-tetramethylurea, 2-pyrrolidone, N-
Methyl-2-pyrrolidone, carbamic acid ester and the like. These solvents can be used in combination. Also,
It may be used in combination with other solvents such as ketone solvents and ether solvents. Examples of the ketone solvent include cyclohexanone, acetylacetone, diisobutylketone, holon, isophorone, methylcyclohexanone, acetophenone, and the like.

(Synthesis conditions) The conditions for the synthesis of the polymer are as follows:
The blending equivalent ratio of the bifunctional heavy epoxy resin and the halogenated bifunctional phenol is as follows: epoxy group / phenolic hydroxyl group = 1
/0.9 to 1 / 1.1. When the phenolic hydroxyl group is less than 0.9 equivalent relative to 1 equivalent of the epoxy group, the phenolic hydroxyl group does not become a high molecular weight linearly, a side reaction occurs, cross-linking occurs, and it becomes difficult to dissolve in a solvent. If it exceeds the equivalent, high molecular weight does not progress. The polymerization reaction temperature is 60-
Desirably, the temperature is 150 ° C. When the temperature is lower than 60 ° C., the reaction for increasing the molecular weight is remarkably slow. The solid content concentration in the polymerization reaction using a solvent may be 50% by weight or less, and more preferably 40% by weight or less. If it exceeds 50% by weight, side reactions increase and it becomes difficult to increase the molecular weight into a linear form, which is not preferable. Thus, the film-forming weight average molecular weight is 100,
A so-called halogenated high molecular weight epoxy polymer of 000 or more can be obtained.

(Crosslinking agent) A compound which is used as a crosslinking agent for the halogenated high molecular weight epoxy polymer to easily control the reactivity of the crosslinking agent and to ensure the storage stability of the varnish. Use masked isocyanates masked (blocked) with. The isocyanate may be any as long as it has two or more isocyanate groups in the molecule, for example, phenols, oximes, hexamethylene diisocyanate masked with a masking agent such as alcohols, diphenylmethane diisocyanate, Examples include isophorone diisocyanate and tolylene diisocyanate. In particular, isophorone diisocyanate and tolylene diisocyanate masked with phenols are preferred for improving the heat resistance of the cured product. The amount of the crosslinking agent is preferably from 0.1 to 1.0 equivalent of the isocyanate group based on 1.0 equivalent of the alcoholic hydroxyl group of the high molecular weight epoxy polymer. When it exceeds 1.0 equivalent, isocyanate remains in the film, and heat resistance and chemical resistance decrease, which is not preferable.

(Polyfunctional Epoxy Resin) As the polyfunctional epoxy resin, any compound having two or more epoxy groups in a molecule may be used. For example, a phenol novolak type epoxy resin and a cresol novolak type epoxy resin may be used. Epoxy resin and alicyclic epoxy resin which are glycidyl ether of phenols such as resin, resol type epoxy resin and bisphenol type epoxy resin, epoxidized polybutadiene, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, isocyanurate type epoxy resin Resin, flexible epoxy resin, etc., any epoxy resin may be used, but in particular, phenolic epoxy resin or a mixture of phenolic epoxy resin and polyfunctional epoxy resin improves heat resistance. Preferred for The amount of this polyfunctional epoxy resin is
20 to 1 based on 100 parts by weight of the high molecular weight epoxy polymer
When the amount is less than 20 parts by weight, the adhesiveness is reduced. When the amount is more than 100 parts by weight, the copper-clad thermosetting resin adhesive film of the B stage is easily cracked, This is not preferred because the properties are reduced. Further, since this polyfunctional epoxy resin acts as an adhesive component and a resin flow at the time of molding, it can be adjusted to an appropriate amount by the thickness of the inner layer copper foil and the density of its circuit. These polyfunctional epoxy resins may be used alone or in combination of two or more.

(Curing Agent) Further, a curing agent for the polyfunctional epoxy resin and, if necessary, a curing accelerator are used. Examples of epoxy resin curing agents and curing accelerators include novolak type phenol resins, dicyandiamide, acid anhydrides, amines, imidazoles, phosphines, and the like. Further, these may be used in combination.

(Additives) It is preferable to further add a silane coupling agent because the adhesiveness of the thermosetting epoxy resin composition, particularly the adhesiveness with a copper foil, is improved. As the silane coupling agent to be added, epoxy silane, amino silane, urea silane and the like are preferable.

(Inorganic Filler) The inorganic filler is used for ordinary resins, and can be used as long as it has a higher elastic modulus than the resin and is electrically insulating. Powder filling of magnesium hydroxide, talc, alumina, magnesia, E glass, silica, titanium dioxide, calcium silicate, aluminum silicate, calcium carbonate, clay, silicon nitride, silicon carbide, aluminum borate, synthetic mica, etc. Material, glass, asbestos, rock wool, short fiber filler such as aramid,
Whisker such as silicon carbide, alumina, aluminum borate and the like can be used. Two or more of these may be used in combination, but aluminum hydroxide, talc, clay, and synthetic mica are particularly preferred because they do not reduce the dispersibility in varnish, storage stability, heat resistance, and adhesion. The amount of the inorganic filler is 10 to 60% by volume in the resin containing the filler. Further, preferably, the inorganic filler is 20 to 60% by volume.
Used in. When the amount of the inorganic filler is 10% by volume or less, the effect on the strength of the film is small. On the other hand, when the amount is 60% by volume or more, the handleability of the film is lowered and the adhesive strength is lowered. Further, as a method of kneading the inorganic filler with the varnish, any of a grinder, a homomixer, a bead mill, a pearl mill, a ball mill and the like may be used.
The kneading temperature may be any temperature as long as the temperature does not coagulate and boil. Also, the inorganic filler is
Any of the materials may be mixed and dispersed in advance.

(Flame Retardant) If necessary, a flame retardant may be added. Examples of the flame retardant include bromine compounds such as tetrabromobisphenol A, decabromodiphenyl ether, brominated epoxy resin and brominated phenol resin. Can be used.

(Step a) A varnish containing the above components is applied to a copper foil and dried by heating to obtain a B-stage copper-clad thermosetting resin adhesive film. The thickness of this resin layer depends on the copper foil thickness of the inner layer circuit,
100 μm is preferred. The B-staged copper-clad thermosetting resin adhesive film is overlaid so that the resin layer of the previously prepared inner layer circuit board and the copper-clad thermosetting resin adhesive film are in contact with each other. Obtain a laminate.

(Step b) An etching resist is formed on the copper foil of the copper-clad laminate with the inner layer circuit, on which the obtained copper-clad thermosetting resin adhesive film is laminated, and is subjected to a commonly used photographic method. Then, a phenomenon and selective etching are performed to form fine openings serving as via holes in the copper foil.
This fine opening becomes the opening of the via hole.
Then, the etching resist is removed.

(Step c) The thermosetting resin adhesive film exposed at the fine opening is etched away with an etching solution containing amide-based solvent, alkali metal compound and alcohol-based solvent until the inner layer circuit is exposed. . The high molecular weight epoxy polymer which is a component of the copper-clad thermosetting resin adhesive film is decomposed by alkali. The etching effect of the resin layer is such that the skeleton of the high molecular weight epoxy polymer is cut and decomposed by the alkali that has permeated the cured film layer in conjunction with the amide-based solvent and alcohol-based solvent. And etched.

The amide solvent may be of any type. For example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N, N, N ',
N'-tetramethylurea, 2-pyrrolidone, N-methyl-2-pyrrolidone, carbamic acid esters and the like.
In particular, N, N-dimethylacetamide, N, N-dimethylformamide, and N-methyl-2-pyrrolidone, which have a large effect of dissolving a cured product having a reduced molecular weight, are preferable. Also, a mixture of these may be used. Further, it may be used in combination with other solvents typified by ketone solvents, ether solvents and the like. An aqueous solution may be used. Ketone solvents that can be used in combination here, for example, acetone, methyl ethyl ketone,
There are 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, cyclohexanone, and the like.

Examples of ether solvents that can be used in combination here include dipropyl ether, diisopropyl ether, dibutyl ether, anisole, phenetole, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and the like. Although the concentration is not particularly limited, if the amide solvent is present in the solution at a concentration of 30 to 95% by weight, the decomposition rate and dissolution rate of the cured product are increased. The alkali metal compound may be any alkali metal compound such as lithium, sodium, potassium, rubidium and cesium, as long as the compound is soluble in an alcoholic solvent, such as lithium, sodium, potassium, rubidium and cesium. There are metals, hydrides, hydroxides and the like. In particular, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferred because they are easy to handle and the decomposition rate of the cured product is high. The concentration is not particularly limited.
It is preferred that the compound is present in the solution at a concentration of １５15% by weight because the decomposition rate of the cured product is increased.

Examples of the alcohol solvent include methanol,
Ethanol, 1-propanol, 2-propanol, 1
-Butanol, 2-butanol, iso-butanol,
tert butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, iso-pentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1- Hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, cyclohexanol, 1-methylcyclohexanol, -Methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether,
Ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether,
Diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propane There are diol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, glycerin, dipropylene glycol and the like. Particularly high solubility of alkali metal compounds, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, tetraethylene Glycol and polyethylene glycol are preferred, and a mixture thereof may be used. The concentration is not particularly limited,
When present at a concentration of 4.5 to 35% by weight during dissolution, the decomposition rate of the cured product is increased, which is preferable. The etching solution composed of each of the above-mentioned components is suitable for the contact time between the thermosetting resin adhesive film and the solution and the temperature of the solution depending on the desired etching rate and degree, so that it is more appropriate for the via hole diameter and thickness. Must be a condition. The etching method can be a spray method, a dip method, or the like, and is not particularly limited.

(Step d) Next, as a plating method for electrically connecting the exposed inner layer circuit and the outer layer copper foil, generally used electroplating is preferable, and electroless copper plating may be used for the small-diameter via hole. . In addition, the electrical connection may be made by applying a conductive paste, drying and curing the paste.

(Step e) Further, an etching resist is formed on the outer layer copper foil, development and selective etching are performed by a generally used photographic method, and a wiring circuit is formed on the outer layer copper foil surface. Is removed to obtain a multilayer printed wiring board in which the inner layer circuit and the outer layer circuit are connected by via holes.

The multilayer printed wiring board obtained as described above is used as an inner layer circuit board, and a copper-clad thermosetting resin adhesive film is further laminated thereon, and this is repeated to form a multilayer circuit board connected by 6 or more via holes. A printed wiring board can also be obtained.

[0042]

Example 1 A bisphenol A type epoxy resin (epoxy equivalent: 172) was used as a bifunctional epoxy resin, and tetrabromobisphenol A (hydroxyl equivalent: 272) was used as a halogenated difunctional phenol. / Phenolic hydroxyl group = 1 / 1.02, lithium hydride as a catalyst in the presence of 0.065 mol with respect to 1 mol of bifunctional epoxy resin, N, N-dimethylacetamide as a solvent The mixture was adjusted so that the solid concentration of the solution was 30% by weight.
A brominated high molecular weight epoxy polymer having a weight average molecular weight in terms of styrene of 300,000 as measured by gel permeation chromatography (GPC) and having a film-forming ability was obtained by heating and polymerizing in the solvent. Isophorone diisocyanate is used as an isocyanate having two or more isocyanate groups in the brominated high molecular weight epoxy polymer, and a phenol novolak resin is used as a masking agent for 2 equivalents of the isocyanate group. It was used so as to be 0.5 equivalent, and was blended so that 0.5 equivalent of isocyanate group was equivalent to 1 equivalent of alcoholic hydroxyl group of the high molecular weight epoxy polymer. For 100 parts by weight of the brominated high molecular weight epoxy polymer, 60 parts by weight of a cresol novolak type epoxy resin (epoxy equivalent: 195) as a polyfunctional epoxy resin and 20 parts by weight of a phenol novolak resin (hydroxyl equivalent: 106) as a curing agent. Parts. Furthermore, as an inorganic filler, an average particle size of 2.5
μm clay was blended so as to be 30% by volume, and kneaded at room temperature for 60 minutes using a grinder to obtain a varnish. This varnish is applied to a roughened surface of a copper foil 3 having a thickness of 18 μm, and dried in a drier at 140 ° C. for 0.1 hr. A thermosetting resin adhesive film was obtained. This copper-clad thermosetting resin adhesive film 21 is overlaid on the previously prepared inner circuit board 1 (shown in FIG. 1A), at a temperature of 170 ° C. and a pressure of 2MP.
Vacuum press molding was performed at 30a for 30 minutes to obtain a copper-clad laminate 4 with an inner layer circuit (shown in FIG. 1 (b)). A dry film for an etching resist is laminated on the surface of the outer layer copper foil of the copper-clad laminate 4 containing the inner layer circuit (shown in FIG. 1C), exposed to ultraviolet rays through a photomask, developed, and developed. 8 is formed, an opening 51 is formed at a position where a via hole is to be formed to have a diameter of 100 μm from which the resist has been removed (shown in FIG. 1D), and a copper foil exposed from the opening is formed. 3 was removed by etching (shown in FIG. 1E). Next, the etching resist 8 was peeled and removed (shown in FIG. 1F). Subsequently, N-methyl-2-pyrrolidone 8 heated to 60 ° C.
An etching solution consisting of 0% by weight, 3% by weight of potassium hydroxide, and 17% by weight of polyethylene glycol is contacted for 30 minutes to remove the cured thermosetting epoxy resin composition by etching, exposing an inner layer circuit, and forming a hole for a via hole. 5 was formed. Here, in the case where removal of the decomposition product is unsafe, ultrasonic waves were continuously applied to wash the inside of the hole with water (FIG. 1).
(G). ). Next, through holes 6 were formed by drilling (shown in FIG. 1 (h)). Continued
Copper plating 7 of 15 to 20 μm was performed to electrically connect the inner layer circuit and the outer layer copper foil and to metalize the inner wall of the via hole 5 and the inner wall of the through hole 6 (FIG. 1).
It is shown in (i). ). Next, an etching resist 7 is formed on the outer layer surface (shown in FIG. 1 (j)), and a wiring circuit is formed by selective etching (shown in FIGS. 1 (k) and 1 (l)). Was removed (shown in FIG. 1 (m)) to obtain a multilayer printed wiring board having four layers.

Example 2 In place of the inorganic filler of Example 1, 30% by volume of aluminum hydroxide having an average particle size of 2.0 μm was used. Further, an etching solution containing 85% by weight of N-methyl-2-pyrrolidone, 2.25% by weight of potassium hydroxide, and 12.75% by weight of diethylene glycol monomethyl ether heated to 60 ° C. was used as the etching solution. The contact film was contacted for 35 minutes to etch the adhesive film to expose the inner layer circuit and form a hole for a via hole, thereby obtaining a similar four-layer multilayer printed wiring board.

Example 3 In place of the inorganic filler of Example 1, 30% by volume of synthetic mica having an average particle size of 2.0 μm was used. Further, N, N-dimethylacetamide 9 heated to 50 ° C. was added to the etching solution.
Using an etching solution consisting of 0% by weight, potassium hydroxide 1% by weight, and diethylene glycol monomethyl ether 9% by weight, this etching solution is brought into contact for 35 minutes to etch the adhesive film, to expose the inner layer circuit, and to form a via hole. Thus, the same four-layer multilayer printed wiring board was obtained.

Example 4 In place of the inorganic filler of Example 1, 15% by volume of clay having an average particle size of 2.5 μm and 15% by volume of aluminum hydroxide having an average particle size of 2.0 μm were used. 80% by weight of N, N-dimethylformamide heated to 50 ° C., 4% by weight of sodium hydroxide, polyethylene glycol 16
Using an etching solution consisting of 4% by weight, this etching solution is contacted for 40 minutes to etch the adhesive film, to expose an inner layer circuit, form a hole for a via hole, and obtain a similar four-layer multilayer printed wiring board. Was completed.

Example 5 In place of the inorganic filler of Example 1, 25% by volume of clay having an average particle size of 2.5 μm was used. 80% by weight of N, N-dimethylformamide heated to 60 ° C., 0.5% by weight of lithium hydroxide, polyethylene glycol 1
Using an etching solution consisting of 9.5% by weight, the etching solution is brought into contact with the etching solution for 40 minutes to etch the adhesive film, thereby exposing the inner layer circuit and forming a hole for a via hole;
A similar four-layer multilayer printed wiring board was obtained.

Example 6 30 parts by weight of a cresol novolak type epoxy resin (epoxy equivalent: 195) as a polyfunctional epoxy resin was added to 100 parts by weight of the high molecular weight epoxy polymer of Example 1, and a bisphenol A type epoxy resin (epoxy Equivalent:
172) and 20 parts by weight of a phenol novolak resin (hydroxyl equivalent: 106) as a curing agent. Otherwise, in the same manner as in Example 1, contact the etchant for 30 minutes to etch the adhesive film, expose the inner layer circuit, form a hole for a via hole, and obtain a similar four-layer multilayer printed wiring board. Was completed.

Example 7 Isophorone diisocyanate was used as the isocyanate having two or more isocyanate groups of Example 1, and a phenol novolak resin was used as a masking agent and activated hydrogen was used as a masking agent for 1.0 equivalent of the isocyanate group. It was used so as to be 0.5 equivalent, and was blended so that 0.3 equivalent of isocyanate group was equivalent to 1 equivalent of alcoholic hydroxyl group of the high molecular weight epoxy polymer. A cresol novolak type epoxy resin (epoxy equivalent: 1) was used as a polyfunctional epoxy resin with respect to 100 parts by weight of a high molecular weight epoxy polymer.
95), 20 parts by weight of a bisphenol A type epoxy resin (epoxy equivalent: 172) and 40 parts by weight of a phenol novolak resin (hydroxyl equivalent: 106) as a curing agent.
0 parts by weight were blended. Further, as an inorganic filler, a clay having an average particle size of 2.5 μm was blended so as to be 30% by volume, and kneaded mechanically at room temperature for 60 minutes to obtain a varnish. Otherwise, in the same manner as in Example 1, contact the etchant for 40 minutes to etch the adhesive film, expose the inner layer circuit, form a hole for a via hole, and obtain a similar four-layer multilayer printed wiring board. Was completed.

Comparative Example 1 In place of the etching solution of Example 1, N heated to 60 ° C.
A four-layered multilayer printed wiring board was produced in the same manner as in Example 1 except that -methyl-2-pyrrolidone was used as an etching solution, but with this etching solution, the adhesive film swelled white, but was not etched. A via hole could not be formed.

Comparative Example 2 The high-molecular-weight epoxy polymer of Example 1 was prepared by using YP50 (trade name, manufactured by Toto Kasei Co., Ltd., trade name, average molecular weight: 68,000) as a phenoxy resin and having two or more isocyanate groups. Isophorone diisocyanate is used as an isocyanate, and a phenol novolak resin is used as a masking agent so that activated hydrogen becomes 2.5 equivalents to 1.0 equivalent of the isocyanate group, and alcoholic hydroxyl groups of a high molecular weight epoxy polymer are used. It was blended so that 0.5 equivalent of isocyanate group was added to 1 equivalent. 60 parts by weight of a cresol novolak type epoxy resin (epoxy equivalent: 195) as a polyfunctional epoxy resin and 20 parts by weight of a phenol novolak resin (hydroxyl equivalent: 106) as a curing agent for 100 parts by weight of a high molecular weight epoxy polymer. did. This varnish is applied to a roughened surface of a copper foil having a thickness of 18 μm, and dried in a drier at 140 ° C. and 0.1 hr. A curable resin adhesive film was obtained. Otherwise, a four-layer multilayer printed wiring board was produced in the same manner as in Example 1, but the adhesive film was not etched by the etching solution.
A via hole could not be formed.

Comparative Example 3 100 parts by weight of a brominated bisphenol A type (epoxy equivalent: 470) as an epoxy resin for prepreg, 5 parts by weight of dicyandiamide as a curing agent, and 0 parts of benzylmethylamine as a curing accelerator. And 2 parts by weight of an epoxy resin varnish dissolved in methyl ethyl ketone, a clay having an average particle size of 2 μm was blended as an inorganic filler in an amount of 30% by volume, and a varnish mechanically stirred at room temperature for 90 minutes was added in advance. It was directly applied on the inner circuit board processed by the circuit processing by a screen printing method, dried at 160 ° C. and 0.1 hr, and then laminated with a copper foil, heated and pressed for lamination and integration. Otherwise, a four-layered multilayer printed wiring board was manufactured in the same manner as in Example 1, but the resin layer was not etched by the etching solution, and a via hole could not be formed.

Comparative Example 4 In place of the copper-clad thermosetting resin adhesive film of Example 1,
An epoxy resin prepreg using a 0.05 mm glass cloth base material was overlaid on an inner circuit board which had been subjected to circuit processing in advance, and a copper foil was overlaid, followed by heating / pressing and laminating and integrating. Otherwise, a four-layered multilayer printed wiring board was manufactured in the same manner as in Example 1, but the resin layer was not etched by the etching solution, and a via hole could not be formed.

(Test Method) The characteristics of the four-layer multilayer printed wiring board in the examples and comparative examples were tested by the following methods. The number of samples in each test was 100. -Copper foil peeling strength The outer layer copper of the copper-clad laminate containing the inner layer circuit during the manufacturing process of the multilayer printed wiring board was pulled in a 90 mm direction with a width of 10 mm, and the peeling strength was measured. -Solder heat resistance The copper-clad laminate containing the inner layer circuit during the manufacturing process of the multilayer printed wiring board was cut into 25 mm x 25 mm, floated in a solder bath at 260 ° C, and measured for the time free of abnormalities such as blistering.・ High temperature and pressure resistance A 2.0 × 2.0 mm tip soldering iron is heated to 300 ° C., and an outer layer circuit of a multilayer printed wiring board is pressed with a constant load of 1,000 gf for 10 seconds by using this soldering iron. A sample with a short circuit between the circuit and the inner layer circuit was determined as x, and a sample without a short circuit was evaluated as ○. Wire bonding properties An IC chip is fixed to the produced multilayer printed wiring board with a die bonding material, and a gold wire having a diameter of 28 μm is used to connect the IC chip to the produced multilayer printed wiring board using a wire bonder HW22U-. H (manufactured by Kyushu Matsushita Electric Co., Ltd.) at a heating temperature of 150 ° C and 2
Wire bonding was performed under the condition of 00 ° C., and the tensile strength of the gold wire bonded was measured using a pull tester PTR-0.
Measured using 1 (trade name, manufactured by Resca Co., Ltd.) and 4 g
Those with f or more were evaluated as ○, and those with less than 4 gf were evaluated as x.

[0054]

[Table 1]

According to the present invention, via holes can be formed at once by chemical etching, and small-diameter processing of 100 μm or less is possible. Therefore, productivity is greatly improved as compared with conventional drilling, and drilling is performed. Difficult diameters became possible. Further, since the copper-clad thermosetting resin adhesive film is used, the configuration at the time of pressing can be simplified, and the productivity is further improved as compared with the conventional prepreg configuration. The resin composition used for the copper-clad thermosetting resin adhesive film has the same general properties as FR-4 grade used for a multilayer printed wiring board, and has improved strength. Therefore, it is extremely useful as a method for manufacturing a multilayer printed wiring board used for high-density mounting in various electronic devices.

[0056]

As described above, according to the present invention, a via hole having excellent mass productivity, sustained reliability, and electrical characteristics can be obtained, and it can be reduced in thickness, has excellent strength, and has excellent surface mounting. A method for manufacturing a multilayer printed wiring board can be provided.

[Brief description of the drawings]

FIGS. 1A to 1M are schematic cross-sectional views in respective steps for explaining one embodiment of the present invention.

FIGS. 2A to 2H are schematic cross-sectional views for explaining a conventional example.

[Explanation of Codes] 1. Inner layer circuit version Adhesive film 21. 2. Copper-clad thermosetting resin adhesive film Copper foil 4. 4. Copper clad laminate with inner layer circuit Hole for via hole 51. Opening 6. Through hole 7. Copper plating 8. Etching resist 9. Prepreg

 ──────────────────────────────────────────────────の Continuing from the front page (72) Katsushi Shibata, 1500 Ogawa, Oji, Shimodate, Ibaraki Prefecture Inside the Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Ayako Matsuo, 1500 Ogawa, Oji, Shimodate, Ibaraki, Hitachi Chemical F-term in the Shimodate Research Laboratory (reference)

Claims (8)

[Claims] 1. A method comprising: a. An epoxy group / phenol hydroxyl group = a bifunctional epoxy resin and a halogenated bifunctional phenol
A high-molecular-weight epoxy polymer having a weight-average molecular weight of 100,000 or more and having a film-forming ability, blended so as to be 1 / 0.9 to 1 / 1.1, and heated and polymerized in the presence of a catalyst; A crosslinking agent, a polyfunctional epoxy resin, a curing agent,
A curing accelerator, if necessary, an adhesive layer of a thermosetting epoxy resin composition containing inorganic filler as a component is formed on a copper foil, to prepare a copper-clad thermosetting resin adhesive film,
A step of laminating an inner layer circuit board on which an inner layer circuit has been formed in advance and a resin surface of a copper-clad thermosetting resin adhesive film and bonding them by heating and pressing to form a laminated board. b. On the copper foil of the copper-clad thermosetting resin adhesive film, an etching resist is formed, and by selectively etching away unnecessary copper foil portions, a fine opening serving as a via hole is formed. Removing. c. The thermosetting epoxy resin composition exposed at the fine opening to be the via hole, an amide-based solvent, an alkali metal compound, an etching solution comprising an alcohol-based solvent,
A step of forming a hole to be a via hole by etching until the inner circuit is exposed. d. A step of plating at least the inner wall of the via hole by metallization to electrically connect the inner layer circuit and the copper foil. e. A step of forming an etching resist on the copper foil of the plated laminate and selectively removing unnecessary copper by etching to form an outer layer circuit and remove the etching resist. A method for manufacturing a multilayer printed wiring board, comprising: 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the inorganic filler is blended in an amount of 10 to 60% by volume of the thermosetting epoxy resin composition. 3. An inorganic filler comprising electrically insulating aluminum hydroxide, magnesium hydroxide, talc, alumina, magnesia, E glass, titanium dioxide, potassium titanate, aluminum silicate, calcium carbonate, clay, silicon nitride. 3. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein a material selected from the group consisting of silicon, silicon carbide, aluminum borate, synthetic mica powder, and a combination thereof is used. 4. An inorganic filler selected from the group consisting of electrically insulating aluminum hydroxide, talc, clay, synthetic mica powder or a combination thereof. 3. The method for producing a multilayer printed wiring board according to any one of 2. 5. An amide-based solvent in an etching solution of a cured thermosetting epoxy resin composition, wherein N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone or a combination thereof is used. 5. A multilayer printed wiring board according to claim 1, wherein an etching solution present in the solution at a concentration of 30 to 95% by weight is used. Method. 6. An alkali metal compound in an etching solution of the cured thermosetting epoxy resin composition, which is selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, and is used in an amount of 0.5 to 15% by weight. 6. An etching solution which is present in a solution at a concentration of 1% by weight.
The method for producing a multilayer printed wiring board according to any one of the above. 7. An alcoholic solvent in the etching solution of the cured thermosetting epoxy resin composition, wherein ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol are used. Use a material selected from the group consisting of monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, tetraethylene glycol, polyethylene glycol, or a combination thereof, and
The method for producing a multilayer printed wiring board according to any one of claims 1 to 6, wherein an etching solution present in the solution at a concentration of 35% by weight is used. 8. The method according to claim 1, wherein a conductive paste is applied, dried and cured to electrically connect the inner layer circuit and the copper foil instead of the plating in the step d. 3. The method for producing a multilayer printed wiring board according to item 1.